1. Field of the Invention
The present invention relates to an improved assembly, referred to as a shock mount, for securing part of a heavy structure, such as a vehicle body, to a support, such as the frame of the vehicle, and absorbing vibrations or shocks between the two structures.
2. Description of the Prior Art
A well known shock isolating mount currently used in the automotive industry for securing and supporting the body or cab of a vehicle on its frame comprises two mating rings of elastically resilient material between which a body mounting part such as an ear protruding from the vehicle is engaged and clamped by a two-part spool that is seated on the vehicle frame and fixed to it by a threaded fastener. The spool parts have flanges which bear against the opposite sides of the mating rings and are threaded together so that by turning one spool part relative to the other the elastic rings and the body mounting part between them are clamped tightly between the flanges. One of the spool parts is a tubular spacer having an annular flange integral with a deep drawn tube that is internally left hand threaded. The other spool part is a thimble having an annular flange integral with a deep drawn tube that is externally left-hand threaded to fit inside and engage its thread with the screw thread of the tubular spacer. A torque nut is welded to the flange face opposite the thimble tube. The torque nut is right hand threaded.
This known shock mount is assembled by inserting the spacer tube through the center of the mating elastic rings and the body mounting part positioned between them, placing the end of the thimble tube in the end of the spacer tube, and turning the thimble to thread it into the spacer tube and clamp the elastic rings tightly together on the body mounting part. Then, the spool assembly and body part is seated in place on the vehicle frame, and the threaded fastener is passed up through an opening in the frame, through the tubes and the assembled spool parts, and is threaded into the nut welded onto the thimble until the entire assembly is fixed securely to the frame.
It has been found that several practical drawbacks impede effective fastening by the prior art assembly.
During production line assembly of the spool parts crossing and jamming of the left-hand thread can and sometimes does occur, preventing the assembly from clamping together properly. An additional drawback of the known assembly becomes apparent if cross-threading of the threaded fastener and the welded nut occurs, because torque applied to the fastener in an attempt to unscrew the threaded fastener can instead cause the left-hand threaded thimble to unscrew from the spacer, jamming the entire assembly so that the unit must be cut off. In addition, it is difficult to get a good thread when manufacturing the tube components. It is also difficult to weld the torque nut onto the spindle flange so that it is properly centered.